An uncommonly satisfying mix of medieval fantasy, high-tech military action and "Mad Max"-style misadventure, "Reign of Fire" imagines an Earth 20 years hence where the human race has been decimated by hordes of flying dragons. Pic could post better-than-average B.O. numbers as midsummer popcorn entertainment before really blazing as a homevid item.

Aptly portentous prologue, set in contempo London, intros Quinn (Ben Thornton) as Brit schoolboy who's in a subway construction site deep below ground when workers inadvertently drill into a massive cave where a long-hibernating fire-breather rests with dozens of dragon eggs.

Unfortunately, the reawakened dragon kills Quinn's engineer mother (Alice Krige) while escaping to the surface. Then the fertilized eggs hatch.

Director Ron Bowman (helmer of 1998's "The X Files" feature spin-off) deftly segues to the rest of his story by way of a dazzlingly edited montage that provides all other necessary exposition. (Images range from ancient manuscript illustrations to faux Time magazine covers while a narrating witness literally takes pen to paper.) In the two decades following the London reawakening, thousands of dragons have overrun the planet, surviving primarily on their favorite cuisine: blackened human beings.

Throughout the globe, pockets of survivors huddle in small, isolated communities. Mindful of their status as members of an endangered species, they keep low profiles, rarely venture alone into open spaces --- and always, even in their group prayers, warn of the need for constant vigilance.

At one such stronghold, a ruined castle in Northumberland, "Reign of Fire" finds the grown-up Quinn (Christian Bale) leading a community that relies on jerry-rigged technology, dwindling artillery and primordial survival instincts. Every so often, some restive souls ignore Quinn's advice and forage for food in nearby fields. But in almost every instance, once these folks have eaten, they are then eaten themselves.

Working from an unexpectedly smart script by Gregg Chabot, Kevin Peterka and Matt Greenberg, Bowman vividly evokes a sense of day-to-day life in a post-apocalyptic dystopia. In one especially clever scene, two community elders entertain children by enacting a key scene from the epic tale of a master storyteller. No, not Homer. Think George Lucas.

A half-hour in, Matthew McConaughey makes a splashy entrance as Denton Van Zan, a gung-ho American commando who's leading the remnants of a search-and-destroy dragon-hunting squad. Van Zan --- a bald, elaborately tattooed hunk with a twangy accent and a badass attitude --- has armored vehicles, an attack helicopter and high-tech weaponry and surveillance equipment. Trouble is, he doesn't have enough men for a strategic incursion into London. He's looking for a few volunteers. And if he can't find volunteers, he'll settle for a few draftees.

Van Zan's plan is to drop specially-trained troops --- nicknamed archangels --- from the chopper and toss disabling nets onto a targeted dragon, after which Van Zan will deliver the coup de grace and the archangels will make safe, parachuted landings. At least, that's how the plan is supposed to work.

One of these dragon-netting missions is impressively rendered in pic's most exciting sequence. Here and elsewhere, the f/x work is at once effective and artfully evasive. Throughout most of "Reign of Fire," Bowman teasingly refrains from giving auds extended glimpses of the rampaging fire-breathers. Which makes it all the more jolting when aud actually does get a full-frontal look in a dragon attack on the castle outpost and, much later, when Van Zan, Quinn and helicopter pilot Alex (Izabella Scorupco) open take on a big bad fire-breather in what's left of London.

In these scenes, Bowman very nearly succeeds in not once making a viewer think of Godzilla's similar penchant for five-alarm fireworks. It should be noted, however, that in the aforementioned montage, there are two or three images that appear to be wink-wink allusions to low-budget Japanese-produced monster rallies of yesteryear.

Even though Gerald Butler provides a few welcome wisecracks as Quinn's second-in-command, "Reign of Fire" is for the most part deadly serious. Even McConaughey, who hasn't had such unabashed fun chewing on scenery and other actors since "The Return of the Texas Chainsaw Massacre" (1994), keeps it close to real. Bale gives a creditable perf as the charismatic leader who's racked with guilt --- he feels responsible for his mother's death --- and resists placing his followers in harm's way.

Pacing is sufficiently fleet between slam-bang action sequences, and secondary roles are more than adequately handled by well-cast supporting players. On the tech level, "Reign of Fire" is a slick, sleek and periodically scary piece of work. During a preview screening, however, soundtrack occasionally seemed wobbly --- snatches of dialogue were incomprehensible, and Edward Shearmur's music reached tinny crescendos.